Low ambient temperature operation management

ABSTRACT

In various implementations, an air conditioner may operate in low ambient temperatures. In some implementations, operations of crankcase heater(s) and/or compressor(s) may be managed. For example, the crankcase heater(s) associated with compressors in which operation is restricted may be allowed to operate. In some implementations, operations of compressors may alternate.

TECHNICAL FIELD

The present disclosure relates to management of low ambient temperature operation in air conditioners.

BACKGROUND

At low ambient temperatures, air conditioners may operate compressors at part load. When the compressors are allowed to operate at part load, the temperature of the compressor that is restricted from operating may lower. For example, since the ambient temperature is low and since the compressor is not operating (e.g., and thus generating heat), the temperature of the compressor that is restricted from operating may be reduced during the part load operation. If the temperature drops below a temperature, such as a manufacturer recommended minimum sump temperature, then oil dilution and/or refrigerant migration may occur.

SUMMARY

In various implementations, an air conditioner may include more than one compressor. The compressors may be allowed full load operations and part load operations, in some implementations. When the operation of the compressors is a part load operation, one or more low ambient temperature protocols may be implemented to inhibit a temperature of a compressor, in which operation is restricted, from reducing below a predetermined low compressors temperature (e.g., manufacturer recommended minimum sump temperature). The low ambient temperature protocols may include managing crankcase heater operations and/or alternating operations of the compressors.

In various implementations, a request for operation of an air conditioner may be received and an operation of compressors of the air conditioner may be determined based at least partially on the received request. A temperature proximate a portion of the air conditioner may be determined. A determination may be made whether the determined temperature is less than a first predetermined low ambient temperature. Operation may be allowed of crankcase heater(s) associated with compressor(s) of the air conditioner, in which operation is restricted, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation.

Implementations may include one or more of the following features. Operation may be restricted of crankcase heater(s) associated with compressor(s), in which operation is restricted, if the ambient temperature is determined not to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a restricted operation. Operation may be restricted of each of the crankcase heater(s) associated with compressor(s), in which operation is allowed, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises allowing operation. The predetermined low ambient temperature may include approximately 60 degrees Fahrenheit. Allowing operation of at least one of the crankcase heaters may include determining an amount of heat to be provided based at least partially on the determined temperature. In some implementations, at least one of the compressors, in which operation is restricted, may be allowed to operate for a first period of time while allowing one or more of the compressors, in which operation is allowed, to be restricted for the first period of time. The compressors may include first compressor(s) and second compressor(s). In some implementations, one or more of the first compressors may be allowed to operate for a first period of time and operation of one or more of the second compressors may be restricted for the first period of time, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation. One or more of the second compressors may be allowed to operate for a second period of time and operation of one or more of the first compressors may be restricted for the second period of time, after the first period of time has elapsed, in some implementations. The first period of time may be approximately the same as the second period of time. In some implementations, a determination may be made whether the determined temperature is less than a second predetermined low ambient temperature. One or more of the first compressors may be allowed to operate for a first period of time and operation of one or more of the second compressors may be restricted for the first period of time, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and not less than the second predetermined low ambient temperature, and if the determined operation of the compressors comprises a part load operation. After the first period of time has elapsed, one or more of the second compressors may be allowed to operate for a second period of time and operation of one or more of the first compressors may be restricted for the second period of time. If the ambient temperature is determined to be less than the second predetermined low ambient temperature and if the determined operation of the compressors includes a part load operation, one or more of the first compressors may be allowed to operate for a third period of time and operation of one or more of the second compressors may be restricted for the third period of time. The third period of time may be less than the first period of time. After the third period of time has elapsed, one or more of the second compressors may be allowed to operate for a fourth period of time and operation of one or more of the first compressors may be restricted for the fourth period of time. The fourth period of time may be less than the second period of time.

In various implementations, a request for operation of an air conditioner may be received and operation of compressors of the air conditioner may be determined based at least partially on the received request. A temperature proximate a portion of the air conditioner may be determined, and a determination may be made whether the determined temperature is less than a first predetermined low ambient temperature. If the ambient temperature is less than the first predetermined low ambient temperature and if the operation of the compressor comprises a part load operation, operation of one or more of the compressors may be restricted for a first period of time and operation of one or more of the compressors may be allowed for the first period of time. After the first period of time has elapse, operation of at least one of the compressors, in which operation was restricted for the first period of time, may be allowed for a second period of time; and operation of at least one of the compressors, in which operation was allowed for the first period of time, may be restricted for the second period of time.

Implementations may include one or more of the following features. The first period of time may be approximately equal to the second period of time. The first period of time and/or the second period of time may be approximately 90 minutes to approximately 120 minutes. In some implementations, a determination may be made whether the ambient temperature is less than a second predetermined low ambient temperature. The second predetermined low ambient temperature may be less than the first predetermined low ambient temperature. If the ambient temperature is less than the second predetermined low ambient temperature and if the determined operation of the compressors includes a restricted operation, then operation of one or more compressors may be restricted for a third period of time. The third period of time may be less than the first period of time. Operation of one or more of the compressors, in which operation was restricted for the third period of time, may be allowed for a fourth period of time. The third period of time may be approximately equal to the fourth period of time. The third period of time and/or the fourth period of time may be approximately 30 minutes to approximately 45 minutes.

In various implementations, a request for operation of an air conditioner may be received and an operation of compressors of the air conditioner may be determined based at least partially on the received request. A determination may be made whether an ambient temperature proximate at least a portion of the air conditioner is less than a first predetermined low ambient temperature. The second predetermined low ambient temperature may be less than the first predetermined low ambient temperature. If the ambient temperature is less than a second predetermined low ambient temperature operation of a crankcase heater associated with one or more of the compressors, in which operation is restricted, may be allowed, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and not less than the second predetermined low ambient temperature, and if the determined operation of the compressors comprises a part load operation. If the ambient temperature is less than the second predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation, then operation of one or more compressors may be restricted and operation may be allowed of crankcase heater(s) associated with one or more of the compressors, in which operation is restricted, for a first period of time. One or more compressors may be allowed to operate for the first period of time. Operation of at least one of the compressors, in which operation was restricted for the first period of time, may be allowed for a second period of time, and operation of at least one of the crankcase heaters associated with one or more of the compressors, in which operation is allowed, may be restricted for the second period of time. Operation of at least one of the compressors, in which operation was allowed for the first period of time, may be restricted for the second period of time.

Implementations may include one or more of the following features. The first period of time may be approximately equal to the second period of time. The first period of time and/or the second period of time may be less than approximately 120 minutes. In some implementations, a determination may be made whether the ambient temperature is less than a third predetermined low ambient temperature. The third predetermined low ambient temperature may be less than the second predetermined low ambient temperature. If the ambient temperature is less than the third predetermined low ambient temperature, the first period of time and/or the second period of time may be reduced in duration. The reduced first period of time and/or the reduced second period of time may be less than approximately 45 minutes.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the implementations will be apparent from the description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an implementation of an example air conditioner.

FIG. 2A illustrates an implementation of an example process to manage crankcase heater operations.

FIG. 2B illustrates an implementation of an example process to manage crankcase heater operations.

FIG. 3 illustrates an implementation of an example process to manage compressor operations.

FIG. 4 illustrates an implementation of an example process to manage air conditioner operations.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

In various implementations, an air conditioner may operate at a variety of ambient conditions. In some implementations, a user may request the delivery of cool air during low ambient temperatures (e.g., below approximately 65 degrees Fahrenheit, below approximately 62 degrees Fahrenheit, and/or from approximately 62 degrees Fahrenheit to approximately 45 degrees Fahrenheit). When the air conditioner operates in response to a request at low ambient temperatures, the air conditioner may allow the compressors to operate at part load. When the compressors are allowed to operate at part load, operations of one or more compressors may be restricted and at least one compressor may be allowed to operate (e.g., as opposed to full load when each compressor of the air conditioner is allowed to operate). When a compressor is restricted from operation, the temperature of the compressor (e.g., sump temperature) may decrease (e.g., when compared to the temperature during operation of the compressor). If a temperature of the compressor decreases below a predetermined low compressor temperature (e.g., provided by a compressor manufacturer, field technician, default value, etc.), oil dilution and/or refrigerant migration may occur. Thus, the air conditioner may implement one or more low ambient temperature protocols to inhibit oil dilution, inhibit refrigerant migration in the compressor, and/or maintain a temperature of the compressor above the predetermined low compressor temperature.

In various implementations, the low ambient temperature protocols may include managing compressor operations and/or crankcase heater operations. For example, the controller may detect low ambient temperatures (e.g., by determining a temperature and comparing it to a predetermined low ambient temperature) and initiate low ambient temperature protocols. The air conditioner (e.g., a controller) may select among the low ambient temperature protocols and allow and/or restrict one or more of the low ambient temperature protocols (e.g., based on the determined temperature proximate the air conditioner, such as an ambient temperature).

FIG. 1 illustrates an implementation of an example air conditioner 100. The air conditioner may include components such as a condenser 110, compressor A 120, compressor B 130, and evaporator 140. As illustrated, each compressor 120, 130 may include a crank case heater 125, 135. Lines (e.g., tubing) may couple various components and allow refrigerant to flow in and/or out of various components of the air conditioner 100.

Fans 160, 170 may cause air to flow through the condenser 110 and/or the evaporator 140. The air conditioner 100 may include more than one fan to provide air flow to the condenser 110 and/or more than one fan to provide air flow to the evaporator 140. As illustrated, the air conditioner 100 may include a first condenser fan 162, a second condenser fan 164, and a third condenser fan 166 to provide air flow to the condenser 110 and a first evaporator fan 172, a second evaporator fan 174, and a third evaporator fan 176 to provide air flow to the evaporator 140.

The condenser 110 may include an appropriate condenser. In some implementations, the condenser 110 may be a microchannel condenser (e.g., condenser with a channel size less than approximately 1 mm). Microchannel condensers may be sensitive to operating conditions during operation of the air conditioner (e.g., when compared with other condensers (e.g., condenser with tube size greater than 5 mm)). For example, microchannel condensers may be sensitive to refrigerant charge (e.g., a level of refrigerant in the system). When a microchannel condenser has a refrigerant charge greater than a maximum operating charge, the pressure in the microchannel condenser may become elevated due to the refrigerant capacity size difference between the microchannel condenser and the evaporator. The high pressures (e.g., pressures greater than approximately 615 psi, with a refrigerant that includes R-410A refrigerant) may cause mechanical failure, including prefailure events, such as excessive wear on parts and/or high-pressure switch activations. Thus, the air conditioner may control the pressure in the system to manage stability and/or inhibit mechanical failure of the air conditioning system.

Fans 160 may provide airflow to the condenser 110, and fans 170 may provide airflow to the evaporator 140. The fan(s) 160, 170 may include any appropriate number of fans, such as one, two, three, or four fans. A fan 160, 170 may be any appropriate type of fan, such as a centrifugal fan. A fan 160, 170 may include more than one fan setting. For example, the fan may be a multi-speed fan and/or a variable speed fan. In some implementations, a fan may include a high setting and one or more low settings. The settings may be associated with the speed at which the impeller of the fan rotates. For example, fan settings may include a high setting, a first low setting, and a second low setting. The second low setting may be associated with a lower fan speed than the first low setting. For example, a fan may allow operation at 800 RPM (rotations per minute), 650 RPM, and/or 330 RPM. In some implementations, a fan may include a low setting and more than one high setting.

The compressors 120, 130 of the air conditioner may include any appropriate arrangement of compressors (e.g., in series and/or in parallel). The compressors 120, 130 may include a tandem compressor system. The tandem compressor system may allow more than one compressor (e.g., compressor A 120 and compressor B 130) to share discharge lines and suction lines.

Compressor A 120 and/or compressor B 130 may include single stage and/or multi-stage (e.g., more than one stage) compressors. Compressor A 120 and compressor B may be independently operable, in some implementations. For example, compressor A 120 may be allowed to operate and compressor B may be restricted from operation.

Compressor A 120 and/or compressor B 130 may include crankcase heaters 125, 135. The crankcase heaters may include any appropriate crankcase heater. For example, the crankcase heater may be a variable wattage crankcase heater, an on/off heater, and/or a multi-stage heater. A crankcase heater may be disposed in a housing of the compressor, in some implementations. A crankcase heater may provide heat to a portion of a compressor (e.g., the crankcase of a compressor). By delivering heat to the crankcase of the compressor, the crankcase heater may inhibit refrigeration migration, inhibit mixing between the refrigerant and the crankcase oil, and/or inhibit condensation of refrigerant in the crankcase. For example, when a compressor has been turned off for a period of time, the temperature of the refrigerant in the compressor may be low and so the crankcase heater may be utilized to increase the temperature of the refrigerant in the crankcase and inhibit mixing with crankcase oil. In various implementations, the air conditioner may utilize the crankcase heater during operations at ambient temperatures in a low ambient temperature range (e.g., below approximately 65 degrees Fahrenheit, below approximately 62 degrees Fahrenheit, and/or from approximately 62 degrees Fahrenheit to approximately 45 degrees Fahrenheit).

The air conditioner may include an expansion device 150, as illustrated. The expansion device may include any device that at least partially expands refrigerant passing through the device. For example, the expansion device 150 may include a thermal expansion valve, an orifice, and/or an electronic expansion valve.

A controller 180 (e.g., a computer) may be coupled (e.g., communicably, such as by wires or linked by Wi-Fi) to component(s) of the air conditioner 100 and control various operations of the component(s) and/or system. For example, the controller 180 may include modules (e.g., instructions), such as an operation module and/or management module, stored in a memory of the controller and executable by a processor of the controller, to perform various operations of the air conditioner 100. The operation module may control operations of the air conditioner 100, such as receiving requests for operation, determining whether to respond to requests for operation, operating various components (e.g., compressors, reversing valves, and/or expansion valves), etc. The management module may control operation and/or restriction of operation of one or more components of the air conditioner 100, such as fan(s), crankcase heater(s), compressor(s), etc. For example, the management module may determine properties of the air conditioner (e.g., temperature proximate a portion of the air conditioner such as ambient temperature and/or pressure of at least a portion of the air conditioner), retrieve one or more predetermined values for properties (e.g., predetermined low ambient temperature(s)), determine settings for crankcase heater(s) and/or compressor(s), allow crankcase heater(s) and/or compressor(s) to operate, restrict crankcase heater and/or compressor operation(s), allow crankcase operation, and/or any other appropriate operation. In some implementations, the management module may manage one or more operations of the air conditioner to maintain sump temperature(s).

The controller 180 may include a memory that stores the modules (e.g., instructions) and/or other data. For example, the memory may store predetermined property values (e.g., predetermined low ambient temperature value(s), predetermined low ambient temperature range(s), predetermined low compressor temperature(s), predetermined operating pressure(s), and/or predetermined operating pressure range(s)); associations between determined properties of the air conditioner and compressor operation(s) and/or crankcase heater operation(s); and/or other appropriate data.

Although FIG. 1 illustrates an implementation of an air conditioner, other implementations may be utilized as appropriate. For example, the air conditioner may include and/or not include any components, as appropriate. The air conditioner may include more than two compressors (e.g., a tandem compressor with four compressors). The air conditioner may include one compressor. In some implementations, the expansion device may include more than one expansion device. The air conditioner may be a heat pump and may include a reversing valve to allow cooling and heating operations. The fans 160 and/or the fans 170 may include a different number or the same number of fans. The fans 160 and/or the fans 170 may include more than three fans. In some implementations, the fans 160 and/or the fans 170 may include less than three fans. In some implementations, one or more of the compressors may not include a crankcase heater.

In some implementations, a portion of the air conditioner 100 may be disposed outside a building (e.g., an “outdoor portion” on the ground proximate a building and/or on a roof of the building) and a portion of the air conditioner 100 may be disposed inside the building (e.g., an “indoor portion”). For example, the outdoor portion may include condenser 110 and fans 160 and the indoor portion may include evaporator 140 and fans 170. In some implementations, such as a rooftop unit, the condenser 110, fans 160, compressor A 120, crankcase heater 125, compressor B 130, crankcase heater 135, evaporator 140, fans 170, and the expansion device 150 may be disposed in the outdoor portion. The outdoor and/or indoor portion may be at least partially disposed in housing(s).

During a cooling cycle of the air conditioner 100, cool air may be provided by blowing air (e.g., from fans 170) at least partially through evaporator 140. The evaporator 140 may evaporate liquid refrigerant in the evaporator. The evaporator may reduce a temperature of the air to generate cool air, and the cool air may be provided to a location (e.g., via ducting). The gaseous refrigerant may exit the evaporator 140, then may be compressed by compressor A 120 and compressor B 130, and delivered to a condenser 110. The condenser 110 may condense the gaseous refrigerant by blowing air (e.g., from fans 160) at least partially through the condenser 110 to remove heat from the gaseous refrigerant.

During air conditioner operation at ambient temperatures in a predetermined ambient temperature range, to inhibit mechanical wear on the compressor and/or to inhibit oil dilution and/or refrigerant migration, the air conditioner may control compressor operations and/or crankcase heater operations.

FIG. 2 illustrates an implementation of an example process 200 for managing crankcase heater operations. A request for operation of an air conditioner may be received (operation 205). A user may request cool air to be provided to a location, for example. A user may provide a request through a thermostat of the air conditioner. The request may include parameters (e.g., setpoint temperature and/or humidity). The controller of the air conditioner may receive the request.

A determination may be made whether an operation of the compressors in response to the received request is a partial load operation (operation 210). For example, the controller may analyze the request and determine settings for one or more of the components of the air conditioner. The air conditioner may include more than one compressor. One or more of the compressors may include a single stage compressor, multi-stage compressor (e.g., more than one stage), and/or a variable speed compressor. The compressors may include operations such a full load and/or partial load. A partial load operation may include restricting operation of at least one compressor and allowing operation of at least one compressor. A full load operation may include allowing operation of each of the compressors of the air conditioner. The operation of a compressor may include a stage at which the compressor operates.

A controller (e.g., module of the controller) may select an operation of a compressor based at least partially on the parameters in the request. For example, the controller may determine an appropriate compressor operation for one or more of the compressors based on a parameter, such as setpoint temperature, in the received request. During low ambient temperatures (e.g., temperatures less than a predetermined low ambient temperature), the difference between the setpoint temperature in a request and the temperature in a location (e.g., to which cool air may be provided) may be small and so the compressors may operate at part load.

A temperature proximate at least a portion of the air conditioner may be determined (operation 220). For example, a temperature proximate an outdoor condenser may be determined. A temperature proximate a housing of a roof top air conditioner unit may be determined. The determined temperature may be approximately equal to the ambient temperature.

Operation of crankcase heater(s) associated with compressor(s) restricted from operation in the part load operation may be allowed (operation 225). For example, if the operation of the compressors includes a part load operation, one more compressors may be restricted from operation and one or more compressors may be allowed to operate (e.g., at one of the stages of operation).

In the compressor(s) that are restricted from operation, the temperature of the compressor or portions there of (e.g., sump temperature) may decrease (e.g., when compared with the temperature during operation of the compressor). A compressor may include a predetermined compressor low temperature. For example, the predetermined compressor low temperature may be based at least partially on a manufacturer's recommended value for lowest temperature. By maintaining a temperature above the predetermined compressor low temperature, mixing between the refrigerant and oil the compressor may be inhibited. Thus, by allowing operation of the crankcase heater in a compressor in which operation is restricted, the temperature in the compressor or portions thereof may be maintained above the predetermined compressor low temperature.

Process 200 may be implemented by various systems, such as system 100. In addition, various operations may be added, deleted, and/or modified. For example, the predetermined low ambient temperature may be less than approximately 75 degrees Fahrenheit, less than approximately 62 degrees Fahrenheit, and/or less than approximately 35 degrees Fahrenheit. In some implementations, more than one predetermined low ambient temperature may be retrieved and compared to the determined temperature. In some implementations, operation may be allowed for each crankcase heater associated with each of the compressors in which operation has been restricted. In some implementations, the amount of power provided by a crankcase heater to a compressor may be fixed (e.g., on or off) and/or alterable (e.g., multi-stage or variable compressor).

FIG. 2A illustrates an implementation of an example process 250 for managing crankcase heater operation. A request for operation of an air conditioner may be received (operation 255). A user may request operation of the air conditioner (e.g., by adjusting a temperature setpoint). A controller may receive the request from the user (e.g., via a thermostat).

Operation of the compressors may be determined based at least partially on the received request (operation 260). The controller of the air conditioner may determine the operation of one or more of the components of the air conditioner, such as the compressor(s), condenser, fan(s), etc. For example, the controller of the air conditioner may allow operation of one or more compressors to facilitate providing cool air to a location to satisfy a received request from a user.

A determination may be made whether the determined operation comprises a partial load operation (operation 265). The controller may determine the operation of the compressor at least partially based on the temperature differential between the temperature of the airflow (e.g., ambient temperature) provided by the fans to the condenser and the set point temperature in the received request. When the temperature differential is small, for example but not limited to, less than 10 degrees, the controller may determine that a part load operation of the compressor may be allowed to satisfy the received request (e.g., provide cool air to decrease the temperature of the location to approximately the setpoint temperature). In some implementations, the controller may determine whether operation of a compressor has been restricted to determine whether a part load operation has been allowed.

A temperature proximate at least a portion of the air conditioner may be determined (operation 270). For example, the air conditioner may include sensors. The sensors may measure temperature and/or allow a controller to determine a temperature proximate at least a portion of the air conditioner. The determined temperature may be approximately the ambient temperature proximate the air conditioner (e.g., proximate the fan associated with a condenser, proximate the condenser, and/or proximate a housing of the air conditioner).

A determination may be made whether the determined temperature is less than a predetermined low ambient temperature (operation 275). The predetermined low ambient temperature (e.g., less than 65 degrees Fahrenheit) may be retrieved from a memory of the air conditioner. The determined temperature and the predetermined low ambient temperature may be compared. The controller (e.g., a module executed by a processor of the controller) may determine whether the determined temperature is less than a predetermined low ambient temperature based at least partially on the comparison.

A crankcase heater operation may be determined at least partially based on the determined temperature for crankcase heater(s) associated with the compressor(s) in which operation is restricted, if the determined temperature is less than the predetermined low ambient temperature (operation 280). In some implementations, the amount of power delivered by the crankcase heater may be determined based at least partially on the determined temperature. For example, if the determined temperature is less than the predetermined low ambient temperature, a formula may be retrieved from a memory to calculate power (e.g., a wattage) input for a variable wattage crankcase heater. The power provided as input to the crankcase heater may be related to the amount of heat provided by the crankcase heater. For example, the wattage may be based at least partially on the determined temperature. In some implementations, the wattage may be determined by the controller based on a formula, such as, but not limited to:

CC wattage %=CC max %−((determined temperature/factor)*(CC max %−CC min %))

where, CC wattage % is the percentage of the maximum wattage that may be provided to the crankcase heater; CC max % is the maximum wattage that may be provided to the crankcase heater to maintain a sump temperature greater than a manufacturer specified sump temperature (e.g., approximately 18 degrees Fahrenheit for R-410A refrigerant) when the determined temperature is a predetermined low value for the air conditioning application (e.g., approximately 0 degrees Fahrenheit for R-410A refrigerant); and CC min % is the minimum wattage that may be provided to the crankcase heater to maintain a sump temperature greater than the manufacturer specified sump temperature when the determined temperature is a predetermined high value for the air conditioning application (e.g., approximately 62 degrees Fahrenheit for R-410A refrigerant).

Thus, the controller may determine the amount of power to be supplied to the crankcase heater, which is correlated to the amount of heat provided by the crankcase heater, based on the formula.

Process 250 may be implemented by various systems, such as system 100. In addition, various operations may be added, deleted, and/or modified. In some implementations, process 250 may be performed in combination with other processes such as process 200. In some implementations, the request may include more than one setpoint. In some implementations, compressor operation may be alternated (e.g., at least one compressor which was restricted from operation may be allowed to operate and at least one compressor which was allowed to operate may be restricted from operating). Each compressor may include a crankcase heater. In some implementations, operation of a crankcase heater may be inhibited when a determined temperature is greater than the predetermined low ambient temperature. In some implementations, an association table may be utilized to determine an operation of a crankcase heater. For example, a first stage of operation may be allowed in a first range of temperatures, a second stage of operation may be allowed in a second range of temperatures, etc.

FIG. 3 illustrates an implementation of an example process 300 to manage compressor operation. A request for operation of an air conditioner may be received (operation 310). The controller may receive the request (e.g., from a user). The controller may analyze the request to determine whether the air conditioner or portions thereof should be allowed to operate to satisfy the request. If the controller determines that the temperature proximate the location is approximately 80 degrees, then the air conditioner may allow operation of one or more components to provide cool air to the location.

A determination may be made whether an operation of the compressors in response to the request comprises a part load operation (operation 320). For example, the air conditioner (e.g., the controller) may determine an operation of the compressors based at least partially on the received request for operation. The controller may then analyze the determined operation to determine if the operation includes a part load operation. In some implementations, the controller may determine whether one or more compressors are restricted from operation to determine whether the operation of the compressors comprises a part load.

A temperature proximate at least a portion of the air conditioner may be determined (operation 330). The controller may determine a temperature (e.g., ambient temperature) proximate at least a portion of the air conditioner, for example, by using sensors. The sensors may transmit a signal to the controller that provides information related to temperatures and the controller may determine a temperature based at least partially on the signal, in some implementations.

A determination may be made whether the determined temperature is less than a predetermined low ambient temperature (operation 340). The controller may retrieve one or more predetermined low ambient temperatures. The determined temperature may be compared to the retrieved predetermined low ambient temperature (e.g., by a module of the controller). The controller may then determine if the determined temperature is less than a predetermined low ambient temperature based at least partially on the comparison.

Operation of the compressors may be alternated if the operation of the compressors comprises a part load operation and if the determined temperature is less than the predetermined low ambient temperature (operation 350). For example, when the compressor operation comprises a part load operation, at least one compressor may be restricted from operating and at least one compressor may be allowed to operate. Alternating the compressors may include allowing one or more first compressors to operate while restricting operation of one or more second compressors for a first period of time and then restricting operation of the first compressor(s) while allowing operation of the second compressor(s) for a second period of time. The first and the second periods of time may be the same or different. In some implementations, operations may be alternated between more than two groups of compressors. For example, a first set of compressors (e.g., one or more compressors) may be allowed to operate while restricting operation of a second set of compressors and a third set of compressors for a first period of time. The first set of compressors and the third set of compressors may then be restricted from operating while the second set of compressors are allowed to operate for a second period of time. The first set of compressors and the second set of compressors may be restricted from operation while the third set of compressors is allowed to operate for a third period of time. The first, second, and/or third period of time may be the same or different. By allowing alternating of the compressor operations, the sump temperature of the compressor may be increased. For example, when a compressor is restricted from operations, the sump temperature of the compressor may decrease. If the sump temperature decreases below a predetermined low compressor temperature, then problems may occur with compressor operation (e.g., mechanical failure, wear, and/or mixing of oil and refrigerant). Thus, by alternating the compressor that is restricted, the sump temperature may be maintained above the predetermined low compressor temperature.

Process 300 may be implemented by various systems, such as system 100. In addition, various operations may be added, deleted, and/or modified. In some implementations, process 300 may be performed in combination with other processes such as process 200 and/or process 250. Predetermined low ambient temperature(s) may include ranges of temperatures. Alternating compressors may include allowing a first set (e.g., one or more) of compressors to operate for a first period of time while restricting operation of a second set (e.g., one or more) of compressors during the first period of time. After the first period of time has elapsed, operation of at least one compressor in the first set of compressor may be restricted for a second period of time. In some implementations, after the first period of time has elapsed, operation of at least one compressor in the second set of compressors may be allowed for the second period of time. The length of time allowed in the first period of time and/or the second period of time may be based on the determined temperature. For example, a greater length of time may be allowed for a first determined temperature than a second determined temperature, when the first determined temperature is greater than the second determined temperature.

In some implementations, the controller may compare the determined temperature to a range(s) of temperatures to determine whether the determined temperature is less than the range of temperatures, within the range of temperatures, and/or above the range of temperatures. The operation of the compressors may be determined based on the relationship of the determined temperature to the range of temperatures. For example, if the determined temperature is within a first range of temperatures, then the compressors may be alternated in a first period of time (e.g., a first compressor may be allowed to operate for a first period of time and then a second compressor may be allowed to operate for a first period of time while the first compressor operation is restricted). If the determined temperature is below the first range of temperatures, then the compressors may be alternated in a second period of time that is less than the first period of time. If the determined temperature is above the first range of temperatures, then alternating the compressors may be restricted. In some implementations, restricting alternating the compressors when temperatures are above a low ambient temperature may reduce wear on the compressors (e.g., since cycling compressors may increase wear and since a sump temperature may not reduce below a predetermined compressor low temperature when determined temperatures are not low ambient temperatures).

In some implementations, the determined temperature may be compared to a second predetermined low ambient temperature. For example, the second predetermined low ambient temperature may be approximately 30 degrees Fahrenheit. The second predetermined low ambient temperature may be stored in a memory of the controller and retrieved. A determination of the length of time to utilize as the period of time (e.g. first period of time, second period of time, and/or third period of time) to allow prior to alternating the compressors may be based on the comparison. For example, the second predetermined temperature may be greater than the first predetermined temperature. Thus, when the determined temperature is less than the first predetermined temperature, the sump temperature of a compressor restricted from operation may decrease more quickly than when the determined temperature is less than the second predetermined low ambient temperature. Thus, the period of time prior to alternating operation of a compressor may be reduced. For example, if the determined temperature is greater than a first predetermined low ambient temperature and less than a second predetermined low ambient temperature, then a first period of time and/or a second period of time (e.g., greater than approximately 90 minutes and/or from approximately 90 minutes to approximately 120 minutes) may be utilized. If the determined temperature is less than a first predetermined low ambient temperature and less than a second predetermined low ambient temperature, then an adjusted first period of time and/or an adjusted second period of time (e.g., greater than approximately 30 minutes and/or from approximately 30 minutes to approximately 45 minutes) may be utilized. The adjusted first period of time may be less than the first period of time and the adjusted second period of time may be less than the second period of time.

In some implementations, the air conditioner may allow operation and/or restrict operation of crankcase heater(s) associated with restricted compressors in addition to alternating compressors. For example, when a compressor is restricted (e.g., during a part load operation) the controller may allow the crankcase heater associated with the compressor to operate (e.g., on and/or in accordance with a wattage determined by a formula). Thus, when first compressor(s) are allowed to operate and second compressor(s) are restricted from operation, the crankcase heater(s) associated with one or more of the second compressor(s) may be allowed. When the first compressor(s) are restricted from operation and the second compressor(s) or a subset thereof are allowed to operate, the crankcase heater(s) associated with the first compressor(s) may be allowed to operate.

In some implementations, a crankcase heater may be utilized with allowing alternating compressors during a part load operation when a determined temperature is less than a second predetermined low ambient temperature. For example, a second predetermined low ambient temperature may be approximately 30 degrees Fahrenheit. When the determined temperature is determined to be less than the second predetermined low ambient temperature, the crankcase heater(s), associated with compressors in which operation is restricted may be allowed to operate. When the determined temperature is determined to be greater than the second predetermined low ambient temperature, the operation of the crankcase heater may be restricted.

FIG. 4 illustrates an implementation of an example process 400 to manage operations of an air conditioner. A request for operation of an air conditioner may be received (operation 410). For example, a module of the controller may receive the request. The request may include parameters (e.g., temperature and/or humidity) to be satisfied by the air conditioner operations. For example, the request may specify a setpoint temperature for a location.

Operation of the compressors and/or crankcase heater may be determined in response to the request (operation 420). The controller (e.g., a module of the controller stored in the memory and executable by a processor) may analyze the request and determine operation(s) for one or more components of the air conditioner. For example, a request may include a setpoint temperature. If the request is for cool air to be provided to a location and the setpoint temperature is greater than a temperature of the location (e.g., as determined by the controller), the air conditioner may restrict operation of one or more components of the air conditioner. If the request is for cool air to be provided to a location and the setpoint temperature is less than a temperature of the location (e.g., as determined by the controller), the air conditioner may allow operation of one or more components of the air conditioner. For example, the controller may allow a full load operation and/or a partial load operation of the compressors. The controller may determine whether to allow crankcase heater operations (e.g., based on whether an air conditioner is shut down, for example for a long period of time).

A temperature proximate at least a portion of the air conditioner may be determined (operation 430). For example, the controller may determine an ambient temperature proximate the air conditioner or portions thereof (e.g., a temperature proximate a condenser and/or housing of the air conditioner). Sensors may be coupled to the controller and may measure the temperature, in some implementations.

A determination may be made whether the determined temperature is less than a predetermined low ambient temperature (operation 440). The predetermined low ambient temperature may be retrieved from a memory of the controller. The predetermined low ambient temperature may be a default value, user specified, and/or specified by a field technician, for example. The predetermined low ambient temperature may be approximately 65 degrees Fahrenheit and/or approximately 45 degrees Fahrenheit. The retrieved predetermined low ambient temperature may be compared to the determined temperature to determine whether the determined temperature is less than the retrieved predetermined low ambient temperature.

Operation of the compressor(s) and/or crankcase heater(s) may be adjusted if the determined temperature is less than the predetermined low ambient temperature (operation 450). For example, if a determination is made that the determined temperature is less than the predetermined low ambient temperature, then operation of the air conditioner may be under low ambient conditions (e.g., less than the predetermined low ambient temperature). Operation during low ambient conditions may cause sump temperatures to decrease and/or other operational problems. Thus, operation of the compressor(s) and/or crankcase heater(s) may be adjusted. For example, operation of the compressor(s) may be alternated and/or the crankcase heater(s) may be allowed to provide heat to compressors in which operation is restricted. The controller may determine whether to allow the compressors to be alternated, whether to allow crankcase heater operations, and/or whether to allow both of the operations (e.g., low ambient temperature protocols).

Process 400 may be implemented by various systems, such as system 100. In addition, various operations may be added, deleted, and/or modified. In some implementations, process 400 may be performed in combination with other processes such as process 200, process 250, and/or process 300. For example, a second predetermined low ambient temperature may be retrieved from a memory of the controller. The second predetermined low ambient temperature may be less than the first predetermined low ambient temperature. For example, the second predetermined low ambient temperature may be approximately 30 degrees Fahrenheit. The determined ambient temperature may be compared to the second predetermined low ambient temperature. If the determined temperature is greater than the second predetermined low ambient temperature and less than the first predetermined ambient temperature, the operation of the compressor or the crankcase heater may be adjusted, in some implementations. For example, an amount of heat provided by the crankcase heater may be adjusted (e.g., by adjusting the power input). If the determined temperature is less than the second determined low ambient temperature, the operation of the compressor and the crankcase heater may be adjusted, in some implementations. For example, the period of time allowed to elapse before alternating the compressor function may be decreased. In some implementations, if the determined temperature is less than the second predetermined low ambient temperature, the controller may allow compressor operations to be alternated and allow crankcase heater operation.

Although an air conditioner providing cool air (e.g., air in which the temperature has been lowered) to a location has been described, a request for operation may cause warm air (e.g., air in which the temperature has been increased) to be provided to a location.

Although a specific controller has been described in FIG. 1, the controller may be any appropriate computer or other programmable logic device. The controller may include a processor that executes instructions (e.g., modules) and manipulates data to perform operations of the controller. Processor may include a programmable logic device, a microprocessor, or any other appropriate device for manipulating information in a logical manner and memory may include any appropriate form(s) of volatile and/or nonvolatile memory, such as RAM and/or Flash memory.

The memory may include data, such as predetermined property values (e.g., temperatures and/or pressure); predetermined properties of low ambient temperature, predetermined properties of pressures outside predetermined operational pressures; predetermined low ambient temperature(s); predetermined high operational pressure values; predetermined low operational pressure values; low ambient temperature protocols; formulas to determine fan settings; tables of associations to determine fan settings and/or crankcase heater settings; and/or any other data useful to the operation of the air conditioner.

In addition, various software may be stored on the memory. For example, instructions (e.g., operating systems and/or other types of software), an operation module and/or a management module may be stored on the memory. The operation module may operate the air conditioner and/or components thereof during normal operations (e.g., operations in which the system operates based at least partially on user requests for operation). The management module may perform one or more of the operations in processes 200, 250, 300, 400, portions thereof, and/or combinations thereof. For example, the management module may receive requests for operations, determine operations of components of the air conditioner based on requests for operations, determine properties; retrieve predetermined property values (e.g., predetermined low ambient temperatures, low compressors temperatures, and/or other predetermined temperature ranges); compare values; determine operations of compressors and/or crankcase heaters; determine whether to retrieve formulas or other analysis techniques; and/or other operations.

In some implementations, modules may be combined, such as into a single module or multiple modules. Operation modules and/or fan management modules may be distinct modules. In an implementation, operation modules and/or fan management modules may include various modules and/or sub-modules.

A communication interface may allow the controller to communicate with components of the air conditioner, other repositories, and/or other computer systems. The communication interface may transmit data from the controller and/or receive data from other components, other repositories, and/or other computer systems via network protocols (e.g., TCP/IP, Bluetooth, and/or Wi-Fi) and/or a bus (e.g., serial, parallel, USB, and/or FireWire). Operations of the air conditioner stored in the memory may be updated and/or altered through the communication via network protocols (e.g., remotely through a firmware update and/or by a device directly coupled to the controller).

The controller may include a presentation interface to present data to a user, such as though a monitor and speakers. The presentation interface may facilitate receipt of requests for operation from users.

A client (e.g., control panel in field or building) may allow a user to access the controller and/or instructions stored on the controller. The client may be a computer system such as a personal computer, a laptop, a personal digital assistant, a smart phone, or any computer system appropriate for communicating with the controller. For example, a technician may utilize a client, such as a tablet computer, to access the controller. As another example, a user may utilize a client, such as a smart phone, to access the controller and request operations.

Although FIG. 1 provides one example of a controller that may be used with the disclosure, controller can be implemented through computers such as servers, as well as a server pool. For example, controller may include a general-purpose personal computer (PC) a Macintosh, a workstation, a UNIX-based computer, a server computer, or any other suitable device. In some implementations, controller may include a programmable logic device. For example, controller may be mounted to a wall of a location in which air conditioning may be provided. According to one implementation, controller may include a web server. Controller may be adapted to execute any operating system including UNIX, Linux, Windows, or any other suitable operating system. Controller may include software and/or hardware in any combination suitable to provide access to data and/or translate data to an appropriate compatible format.

Various implementations of the systems and techniques described herein can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include implementations in one or more computer programs that are executable and/or interpretable on a programmable system, including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the term “machine-readable medium” refers to any computer program product, apparatus and/or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and/or data to a programmable processor. The machine-readable signal(s) may be non-transitory waves and/or non-transitory signals.

Although users have been described as a human, a user may be a person, a group of people, a person or persons interacting with one or more computers, and/or a computer system.

It is to be understood the implementations are not limited to particular systems or processes described which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting. As used in this specification, the singular forms “a”, “an” and “the” include plural referents unless the content clearly indicates otherwise. Thus, for example, reference to “an operation” includes a combination of two or more operations and reference to “a crankcase heater” includes different types and/or combinations of crankcase heaters.

Although the present disclosure has been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

1. A method comprising: receiving a request for operation of an air conditioner; determining an operation of compressors of the air conditioner based at least partially on the received request; determining a temperature proximate a portion of the air conditioner; determining if the determined temperature is less than a first predetermined low ambient temperature; and allowing operation of one or more crankcase heaters associated with one or more compressors of the air conditioner in which operation is restricted, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation.
 2. The method of claim 1, further comprising: restricting operation of one or more crankcase heaters associated with one or more compressors in which operation is restricted, if the ambient temperature is determined not to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a restricted operation.
 3. The method of claim 1, further comprising: restricting operation of each of the one or more crankcase heaters associated with one or more compressors in which operation is allowed, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises allowing operation.
 4. The method of claim 1, wherein the predetermined low ambient temperature comprises approximately 60 degrees Fahrenheit.
 5. The method of claim 1, wherein allowing operation of at least one of the crankcase heaters comprises determining an amount of heat to be provided based at least partially on the determined temperature.
 6. The method of claim 1, further comprising: allowing at least one of the compressors, in which operation is restricted, to operate for a first period of time while allowing one or more of the compressors, in which operation is allowed, to be restricted for the first period of time.
 7. The method of claim 1, wherein the compressors comprise one or more first compressors and one or more second compressors, and further comprising: allowing one or more of the first compressors to operate for a first period of time and restricting operation of one or more of the second compressors for the first period of time, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation; and allowing one or more of the second compressors to operate for a second period of time and restricting operation of one or more of the first compressors for the second period of time, after the first period of time has elapsed.
 8. The method of claim 7, wherein the first period of time is approximately the same as the second period of time.
 9. The method of claim 7, further comprising: determining if the determined temperature is less than a second predetermined low ambient temperature; allowing one or more of the first compressors to operate for a first period of time and restricting operation of one or more of the second compressors for the first period of time, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and not less than the second predetermined low ambient temperature, and if the determined operation of the compressors comprises a part load operation; allowing one or more of the second compressors to operate for a second period of time and restricting operation of one or more of the first compressors for the second period of time, after the first period of time has elapsed; allowing one or more of the first compressors to operate for a third period of time and restricting operation of one or more of the second compressors for the third period of time, if the ambient temperature is determined to be less than the second predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation, wherein the third period of time is less than the first period of time; and allowing one or more of the second compressors to operate for a fourth period of time and restricting operation of one or more of the first compressors for the fourth period of time, after the third period of time has elapsed, wherein the fourth period of time is less than the second period of time.
 10. A method comprising: receiving a request for operation of an air conditioner; determining an operation of compressors of the air conditioner based at least partially on the received request; determining a temperature proximate a portion of the air conditioner; and determining if the determined temperature is less than a first predetermined low ambient temperature; wherein if the ambient temperature is less than the first predetermined low ambient temperature and if the operation of the compressor comprises a part load operation, the method further comprising: restricting operation of one or more of the compressors for a first period of time; allowing operation of one or more of the compressors for the first period of time; and after the first period of time has elapsed: allowing operation of at least one of the compressors in which operation was restricted for the first period of time for a second period of time; and restricting operation of at least one of the compressors in which operation was allowed for the first period of time for the second period of time.
 11. The method of claim 10, wherein the first period of time is approximately equal to the second period of time.
 12. The method of claim 10, wherein at least one of the first period of time or the second period of time comprises approximately 90 minutes to approximately 120 minutes.
 13. The method of claim 10, further comprising: determining if the ambient temperature is less than a second predetermined low ambient temperature, wherein the second predetermined low ambient temperature is less than the first predetermined low ambient temperature; wherein if the ambient temperature is less than the second predetermined low ambient temperature and if the determined operation of the compressors comprises a restricted operation: restricting operation of one or more compressors for a third period of time, wherein the third period of time is less than the first period of time; and allowing operation of one or more of the compressors in which operation was restricted for the third period of time for a fourth period of time.
 14. The method of claim 13, wherein the third period of time is approximately equal to the fourth period of time.
 15. The method of claim 13, wherein at least one of the third period of time or the fourth period of time comprises approximately 30 minutes to approximately 45 minutes.
 16. A method comprising: receiving a request for operation of an air conditioner; determining an operation of compressors of the air conditioner based at least partially on the received request; determining if an ambient temperature proximate at least a portion of the air conditioner is less than a first predetermined low ambient temperature; determining if the ambient temperature is less than a second predetermined low ambient temperature, wherein the second predetermined low ambient temperature is less than the first predetermined low ambient temperature; and allowing operation of a crankcase heater associated with one or more of the compressors in which operation is restricted, if the ambient temperature is determined to be less than the first predetermined low ambient temperature and not less than the second predetermined low ambient temperature, and if the determined operation of the compressors comprises a part load operation; wherein if the ambient temperature is less than the second predetermined low ambient temperature and if the determined operation of the compressors comprises a part load operation: restricting operation of one or more compressors for a first period of time; allowing operation of one or more crankcase heaters associated with one or more of the compressors in which operation is restricted for the first period of time; allowing operation of one or more compressors for the first period of time; allowing operation of at least one of the compressors in which operation was restricted for the first period of time for a second period of time; restricting operation of at least one of the crankcase heaters associated with one or more of the compressors in which operation is allowed for the second period of time; and restricting operation of at least one of the compressors in which operation was allowed for the first period of time for the second period of time.
 17. The method of claim 16, wherein the first period of time is approximately equal to the second period of time.
 18. The method of claim 16, wherein at least one of the first period of time or the second period of time is less than approximately 120 minutes.
 19. The method of claim 16, further comprising: determining whether the ambient temperature is less than a third predetermined low ambient temperature, wherein the third predetermined low ambient temperature is less than the second predetermined low ambient temperature; and if the ambient temperature is less than the third predetermined low ambient temperature, reducing at least one of the first period of time or the second period of time.
 20. The method of claim 19, wherein at least one of the reduced first period of time or the reduced second period of time is less than approximately 45 minutes. 